In this study, we used a transgenic medaka osteoporosis model, where excessive osteoclast formation is triggered by inducible RANKL expression.(18) Upon RANKL induction, macrophages migrate to the vertebral column where they eventually mature into ctsk‐positive osteoclasts.(19) In the present study, we describe the dynamics of macrophage migration and their close interaction with bone‐lining osteoblasts. Here, TNFSF11 is linked to osteoporosis.